package com.yycx.common.utils;

import lombok.extern.slf4j.Slf4j;
import org.apache.tomcat.util.codec.binary.Base64;

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

/**
 * RSA加解密工具
 *
 * @author sdevil507
 * created on 2021/5/27
 */
@Slf4j
public class RsaUtil {

    /**
     * RSA公钥加密
     *
     * @param str       加密字符串
     * @param publicKey 公钥
     * @return 密文
     * @throws Exception 加密过程中的异常信息
     */
    public static String encrypt(String str, String publicKey) throws Exception {
        //base64编码的公钥
        byte[] decoded = Base64.decodeBase64(publicKey.getBytes());
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("gbk")));
        return outStr;
    }

    /**
     * RSA私钥解密
     *
     * @param str        加密字符串
     * @param privateKey 私钥
     * @return
     * @throws Exception 解密过程中的异常信息
     */
    public static String decrypt(String str, String privateKey) throws Exception {
        //64位解码加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("gbk"));
        //base64编码的私钥
        byte[] decoded = Base64.decodeBase64(privateKey.getBytes());
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }

    public static Map<String, Object> genKeyPair() throws NoSuchAlgorithmException {
        Map<String, Object> keyMap = new HashMap<>(2);
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器，密钥大小为96-1024位
        keyPairGen.initialize(1024, new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私钥字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 将公钥和私钥保存到Map
        //0表示公钥
        keyMap.put("publicKey", publicKeyString);
        //1表示私钥
        keyMap.put("privateKey", privateKeyString);
        return keyMap;
    }

    public static void main(String[] args) throws Exception {
        //生成公钥和私钥
        Map<String, Object> keyMap = genKeyPair();
        //加密字符串
        String message = "df723820";
        System.out.println("随机生成的公钥为:" + keyMap.get("publicKey"));
        System.out.println("随机生成的私钥为:" + keyMap.get("privateKey"));
        String messageEn = encrypt(message,keyMap.get("publicKey").toString());
        System.out.println("加密前的字符串为:"+message);
        System.out.println("加密后的字符串为:" + messageEn);
        String messageDe = decrypt(messageEn,keyMap.get("privateKey").toString());
        System.out.println("还原后的字符串为:" + messageDe);
    }



}